This setting of black-out dates is a good way to prevent your customers from either getting quotes or booking events during specific dates that you are unavailable. For example: Many people use black-out dates for vacations, holidays or for large booked events.
Use the "Shown Unavailable" setting if you are not allowing quotes and want items to display unavailable for the dates specified.
When showing the black-outs as unavailable, if you have your Online Quoting settings set to show the customer your availability, black-out availability will be included. On the admin side, items will show in red and cause the lead/event to have a conflict flag with black-out as the reason when you click the red availability number. You can override this by moving the status of the lead up to a different status (one that is reserving the inventory). At that point, we assume you are intentionally overriding your black-out and booking an event manually. You will no longer see the items in red or showing a conflict even though the black-out exists. You may still be warning messages, though.
You do not have to enter a reason for blacking out certain dates, but you do have the ability to do so if you wish. If you opt to enter in a reason for the black-out date(s), be advised that this will display to your customers. Most companies do not want their customers to know they are going on vacation so they enter in "Booked for a large event".
Black-out Dates will not affect existing booked events, so it can be used to prevent further bookings if a particular date gets too busy to accommodate any more events.
The black-out start date will be the date you are planning to start your black-out. Black-out end date will be when you are returning to normal business hours.
Please note, black-out dates are not the same as maintenance. Black-out dates will be for all inventory. For maintenance check-in/check-out, please see this article.